Waxy Maize Starch: What the Research Says

Quick summary: Waxy maize starch is sold as a super-fast carb for workouts, but the research doesn’t back that up. In human studies it raised blood sugar and insulin less than glucose or maltodextrin, and it refilled muscle fuel no better than ordinary glucose. It works fine as a carbohydrate, just not as anything special.

What is waxy maize starch?

Waxy maize starch comes from a type of corn whose starch is almost entirely amylopectin, a large, tree-like chain of glucose molecules with lots of branches. Regular corn starch also contains amylose, a straighter glucose chain that the body digests more slowly. In one sports study, the waxy starch used was 100% amylopectin and the “resistant” starch was 100% amylose [1].

Supplement marketing often claims that because waxy maize starch is so branched, it gets digested and absorbed faster than dextrose (plain glucose) or maltodextrin, and so refills your muscles’ stored fuel (glycogen) faster after training. Let’s look at what the studies actually found.

Is waxy maize starch a fast carb?

Not according to the human data. A Purdue University trial gave 12 young, healthy adults 50 g of carbohydrate as waxy maize starch, a maltodextrin and sugar mix, or white bread on separate days [2]. Compared with the maltodextrin mix, waxy maize starch led to lower blood sugar (glucose) and insulin responses over four hours, mostly because the rise in the first hour was blunted. The researchers describe waxy maize starch as a slow-digesting starch, the opposite of the marketing claim.

An earlier study in 10 competitive cyclists found the same pattern at rest: a glucose drink pushed blood sugar and insulin higher than the same amount of waxy starch [3].

A slower, gentler rise in blood sugar isn’t a bad thing. It just means waxy maize starch isn’t the “fastest” carb on the shelf.

Waxy maize starch before a workout

In that cyclist study, the riders drank 1 g of carbohydrate per kg of body weight (as glucose, waxy starch or resistant starch) or a sugar-free placebo 30 minutes before 90 minutes of steady cycling, followed by a 30-minute performance ride [3]. They did more work after glucose (434 kJ) or waxy starch (428 kJ) than after the placebo (403 kJ).

So carbs before a long ride helped, but waxy maize starch did no better than plain glucose. It’s also a small study of 10 men from 1996, so it can’t tell us much about small differences.

Does waxy maize starch refill glycogen faster?

This is the main selling point, and the evidence is thin. In a companion study, eight male cyclists did a hard ride to drain their muscle glycogen, then ate a high-carb diet for the next 12 hours with all the carbohydrate coming from glucose, maltodextrin, waxy starch or resistant starch [1].

Twenty-four hours later, muscle biopsies showed glycogen had risen by roughly:

• Glucose: +198 mmol/kg
• Waxy starch: +172 mmol/kg
• Maltodextrin: +137 mmol/kg
• Resistant (high-amylose) starch: +91 mmol/kg

Only the resistant starch was clearly worse. Waxy starch was not better than glucose, and a 30-minute time trial the next day showed no difference in performance between any of the carbs [1].

Waxy maize starch vs. “SuperStarch” (modified waxy maize)

Some newer products use waxy maize starch that has been heat-and-moisture treated (hydrothermally modified) to make it digest even more slowly. These are marketed for steady energy rather than speed, and they’ve been studied a bit more:

• In nine trained cyclists, the modified starch caused a smaller blood sugar and insulin spike than maltodextrin and more fat breakdown during a long ride [4].
• In 10 male cyclists, taking it before and during a 3-hour ride increased fat burning but didn’t improve sprint performance compared with a sugar drink, and it caused more nausea [5].
• In 10 trained runners, taking it before running made no difference to 5-km time-trial performance [6].
• In 11 university soccer players, it seemed to protect dribbling and passing skills late in a simulated match compared with dextrose, though sprint performance was the same [7].

Overall: these modified starches change which fuel your body burns, but so far they haven’t reliably improved performance, and the studies are small.

Don’t mix it up with “high-molecular-weight” carbs

You may see claims that a very large starch-based carb refills glycogen faster than glucose. Those results come from studies of a different product, a very-high-molecular-weight glucose polymer. In one study it sped up glycogen refilling in the first two hours after exercise [8], and in another it improved a cycling time trial two hours later [9]. These findings don’t automatically apply to ordinary waxy maize starch, which behaved like a slow carb in the studies above.

What actually matters for refueling

For most people who train once a day, the type of carb matters much less than eating enough carbohydrate overall. The International Society of Sports Nutrition says glycogen stores are maximized with a high-carb diet of 8 to 12 g of carbohydrate per kg of body weight per day, which is aimed at hard-training athletes [10].

Only when you need to refuel quickly (less than about four hours before your next session) does it recommend eating about 1.2 g/kg of carbohydrate per hour, favoring high-glycemic carbs such as glucose, or adding some protein [10]. If you have a day between workouts, regular meals do the job. (More on that in our posts on the post-workout “anabolic window” and taking creatine with carbohydrates.)

Is waxy maize starch safe?

Waxy maize starch is a food starch, so for most healthy people it’s simply a source of carbohydrate calories. Big carb drinks of any kind can upset some people’s stomachs during exercise, and in one study the modified version caused more nausea than a sugar drink [5]. If you have diabetes or another condition affected by blood sugar, check with your doctor before adding a carbohydrate supplement.

The bottom line on waxy maize starch

Waxy maize starch isn’t a faster carb than dextrose or maltodextrin. In human studies it raised blood sugar and insulin more slowly, refilled glycogen no better than glucose and didn’t improve performance compared with other carbs. If you like it, it’s a perfectly good carbohydrate. But if you’re paying extra for it because of “fast absorption” claims, plain dextrose, maltodextrin or ordinary carb-rich food will do the same job.

Browse more of our carbohydrate articles.

This article is for general information only and isn’t medical advice. Talk to your doctor or another qualified health professional before starting a new supplement. See our medical disclaimer.

References

1. Jozsi AC, Trappe TA, Starling RD, et al. The influence of starch structure on glycogen resynthesis and subsequent cycling performance. Int J Sports Med. 1996;17(5):373-378. doi:10.1055/s-2007-972863
2. Sands AL, Leidy HJ, Hamaker BR, Maguire P, Campbell WW. Consumption of the slow-digesting waxy maize starch leads to blunted plasma glucose and insulin response but does not influence energy expenditure or appetite in humans. Nutr Res. 2009;29(6):383-390. doi:10.1016/j.nutres.2009.05.009
3. Goodpaster BH, Costill DL, Fink WJ, et al. The effects of pre-exercise starch ingestion on endurance performance. Int J Sports Med. 1996;17(5):366-372. doi:10.1055/s-2007-972862
4. Roberts MD, Lockwood C, Dalbo VJ, Volek J, Kerksick CM. Ingestion of a high-molecular-weight hydrothermally modified waxy maize starch alters metabolic responses to prolonged exercise in trained cyclists. Nutrition. 2011;27(6):659-665. doi:10.1016/j.nut.2010.07.008
5. Baur DA, Vargas FC, Bach CW, Garvey JA, Ormsbee MJ. Slow-absorbing modified starch before and during prolonged cycling increases fat oxidation and gastrointestinal distress without changing performance. Nutrients. 2016;8(7):392. doi:10.3390/nu8070392
6. Baur DA, Willingham BD, Smith KA, et al. Adipose lipolysis unchanged by preexercise carbohydrate regardless of glycemic index. Med Sci Sports Exerc. 2018;50(4):827-836. doi:10.1249/MSS.0000000000001498
7. Quinones MD, Lemon PWR. Hydrothermally modified corn starch ingestion attenuates soccer skill performance decrements in the second half of a simulated soccer match. Int J Sport Nutr Exerc Metab. 2019;29(5):498-504. doi:10.1123/ijsnem.2018-0217
8. Piehl Aulin K, Söderlund K, Hultman E. Muscle glycogen resynthesis rate in humans after supplementation of drinks containing carbohydrates with low and high molecular masses. Eur J Appl Physiol. 2000;81(4):346-351. doi:10.1007/s004210050053
9. Stephens FB, Roig M, Armstrong G, Greenhaff PL. Post-exercise ingestion of a unique, high molecular weight glucose polymer solution improves performance during a subsequent bout of cycling exercise. J Sports Sci. 2008;26(2):149-154. doi:10.1080/02640410701361548
10. Kerksick CM, Arent S, Schoenfeld BJ, et al. International Society of Sports Nutrition position stand: nutrient timing. J Int Soc Sports Nutr. 2017;14:33. doi:10.1186/s12970-017-0189-4